The long-term objective of the research proposed in this application is to enhance the motor recovery and as a consequence elicit functional changes in certain patient populations by means of upper extremity trajectory modification through auditory and visual feedback. There are four specific aims of the project. First, a prototype feedback training device will be designed and fabricated for commercial medical use. Second, a formal treatment protocol will be developed. Third, the system will be validated at multiple sites with chronic light and left hemiplegic stroke patients, acute right and left hemiplegic stroke patients, and elderly, nursing home residents with evidence of osteoarthritis of the upper limbs. Fourth, functional attributes, i.e., activities of daily living/self.care skills subserved by reaching, of all patients will be examined prior to and following therapeutic intervention. The technological innovation of the proposed work lies in the adaptation of state-of-the-art kinematic technology to physiological investigations, the consideration of different synergy patterns in the task requirements, the emphasis on training tasks that are near-natural and hence functionally meaningful, and the use of regulated sensory feedback to effect improvement. The proposed research will result in a prototype system, consisting of hardware, software, and treatment protocols for trajectory modification through the use of feedback, that has been tested in several rehabilitation settings, thus defining a large commercial market. If the study is also able to establish statistically significant functional improvements as a result of the feedback training, the potential commercial applications of the system will be extensive. PROPOSED COMMERCIAL APPLICATION: The commercial application of the resulting system is predicated on the inexpensiveness of the intended solution. The final system will be designed to be financially acceptable to major rehabilitation clinics as an augmentation to conventional therapy, as well as to be affordable by individual researchers and clinicians. It should also be possible to configure the device as a home- based rental system for patient or family directed therapy, with the potential to reduce rehabilitation costs.